1. Field of the Invention
The present invention relates to a touched state recognition apparatus for a matrix type touch panel and a control method thereof, and in particular to an improved touched state recognition apparatus for a matrix type touch panel and a control method thereof which are capable of preventing an erroneous touched state recognition when two touch switches are concurrently touched and avoiding a problem which occurs while a touch switch is not touched.
2. Description of the Conventional Art
As shown in FIG. 1, the conventional touched state recognition apparatus for a matrix type touch panel includes a touch panel 1 for recognizing a touched state thereof by a user, a memory 2 for storing a graphic data GRD which is used for executing a screen control program, a microprocessor 3 for applying a checking signal VI to the touch panel 1, detecting a detection signal VO corresponding to a switch touched by a user, and recognizing whether a predetermined region of the touch panel 1 is touched by the user, reading a graphic data GRD from the memory 2, and executing a screen control program, a graphic controller 4 for receiving the graphic data GRD read from the memory 2, through the microprocessor 3, and a display device 5 for displaying a graphic signal from the graphic controller 4.
Here, as shown in FIG. 2, the touch panel 1 includes an upper plate 1A made of a synthetic resin and having electrodes A through G and a lower plate having electrodes A' through F'.
As shown in FIG. 3, the operation of the touch panel 1 will now be explained in the case that the number of touch regions are 42, 7 in the horizontal direction and 6 in the vertical direction.
5 voltage (hereinafter called as a checking signal VI) is applied to the electrode A of the upper plate 1A, and 0 voltage is applied to the remaining electrodes B through G, and then the electrodes A' through F' of the lower plate 1B are checked whether 5 voltage (hereinafter called as a detection signal VO) is applied thereto.
The above-described operation is repeatedly performed with respect to the electrodes B through G of the upper plate 1A, and the detection signal VO is detected with respect to the electrodes A' through F' of the lower plate 1B.
If a hatched region of FIG. 3 is touched, it is easily judged that the electrode D of the upper plate 1A and the electrode D' of the lower plate 1B are touched by the above-described manner.
The operation that the touched state of the touch panel 1 and the graphic data corresponding thereto are displayed will now be explained with reference to FIG. 1.
First, the touch panel 1 is touched in order to obtain an information that a user wants, the microprocessor 3 applies the checking signal VI to the touch panel 1 and receives an output signal VO from the touch panel 1 for checking whether a predetermined switch is touched.
Then, the microprocessor 3 judges whether the detected region corresponds to a predetermined touch switch and executes the screen control program for displaying a graphic information corresponding to the touch switch. At this time, the graphic data GRD is read from the memory 2 and is transmitted to the graphic controller 4.
The graphic controller 3 outputs a graphic signal GRS to be displayed on the display device 5, so that the graphic information corresponding to the touched touch switch is displayed.
Then, the user sees the screen and obtains a desired information displayed thereon.
If the user a user wishes to obtain another information, the user touches the touch panel 1. The remaining operation thereafter is the same as described above.
However, there is a limit in the resolution of the conventional matrix type touch panel, namely, in the size of the region in which the upper plate 1A is formed across the lower plate 1B. Generally, the size of a region of the touch panel 1B is 5 mm to 15 mm. Therefore, when defining the shape of a touch switch on the touch panel, the shape thereof should match with the resolution thereof. If the shape of the touch switch is not matched with the resolution thereof, the touched state of the touch panel may not be recognized.
Namely, assuming that the shapes of the touch switches TSW1 and TSW2 are defined on the screen as shown in FIG. 3, when a user touches a hatched region, it may be judged that the first touch switch TSW1 and the second touch switch TSW2 are concurrently touched, thus causing an erroneous recognition.